摘要:

ExtractIn order to test the role of diffusing capacity in determining the arterial oxygen tension of newborn infants, pulmonary diffusing capacity for carbon monoxide (DLco) was measured in 21 healthy infants ranging in birth weight from 765 to 4,720 g. DLcoin infants without respiratory distress correlated well with lung volume (r= 0.76,P< 0.001). A smaller correlation (r= 0.39,P< 0.01) was obtained between DLcoand arterial oxygen tension. DLcoper unit volume of lung is similar when healthy premature infants, full term infants, and normal adults are compared.The wide range of normal values obtained in resting infants and the lack of correlation with arterial oxygen tensions are similar to observations made in adults.SpeculationDiffusion “block” was not demonstrable in this study, even in infants with mild hypoxemia. These data, in conjunction with other studies reviewed in this report, suggest that lung volume plays a critical role in the level of arterial oxygen tension in newborn infants.

ISSN:0031-3998    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

ExtractSkin reflectance in red, green, and blue light was measured at the sternum of 99 Caucasian infants ranging in gestational age from 26 to 44 weeks. Skin reflectance was consistently higher in female infants, but this difference was not statistically significant. Highly significant (P< 0.001) increases in reflectance at all wave lengths were found when sternal reflectance during the first 48 hr of life was related to gestational age. The dispersion of data points about the regression line does not permit this method to be relied upon as the sole means of determining gestational age of infants. Serial studies indicate that reflectance increases in premature infants not given phototherapy, whereas premature infants receiving photo-therapy show a fall in reflectance for the duration of therapy. This suggests that phototherapy may cause tanning of the skin.SpeculationReflectance spectrometry provides a safe, noninvasive method to assess human newborn skin maturation and may also be a means to determine effects of various therapeutic regimens on the skin.

ISSN:0031-3998    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

ExtractThe present experiments were undertaken to study the effect of exogenous corticosteroids on carbonic anhydrase (CA) activity in fetal erythrocytes. Rabbit fetuses from 24 days of gestation to term (31 days) were injected intraperitoneally with either 0.2 ml of 0.9% saline or 2.5 mg hydrocortisone succinate. Nonoperated, noninjected animals served as controls. Carbonic anhydrase activity measured at 24 hr after injection was increased in the saline-injected group at all ages studied when compared with the noninjected fetuses. A marked increase (2− to 7-fold) in enzyme activity was demonstrated after steroid injection at 24 but not 48 hr after treatment. An increase in CA activity was also demonstrated after incubating fetal erythrocytes for 2, 4, and 8 hr in the presence of hydrocortisone succinate. It is suggested that low CA activity in infants with hyaline membrane disease (HMD) may reflect lack of enhancement by steroid.SpeculationGlucocorticoids are probably important in the enhancement of the development of numerous organ systems, including lung, gut, and blood, in preparation for extrauterine life. Low CA activity in the cord blood of infants with HMD may reflect a lack of steroid activation of a number of fetal enzyme systems, including those necessary for surfactant synthesis.

ISSN:0031-3998    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

ExtractSpectrophotometric characteristics of bilirubin at low concentrations (0.005–2.500 mg/100 ml) have been studied under various physical conditions in order to gain a better understanding of the state of bilirubin when preparing “solutions” for laboratory use. Standing, minimal shaking, or stirring of the bilirubin preparations at pH 7.4 progressively reduced and altered the maximal spectral absorption of bilirubin (440 nm) in aqueous buffered media. The shift to 415–420 nm is attributed to oxidation of the pigment whereas shoulder formation is attributed to the formation of large size particles (flocculants). In the presence of antioxidants (L-ascorbic acid and nitrogen gas) and EDTA the maximal absorption peak remained at 440 nm but decreased in magnitude concomitant with development of a progressively increasing shoulder at 480–560 nm. In the absence of antioxidants and EDTA maximal absorption shifted to 415–420 nm and the magnitude of 480–560 nm shoulder formation was less. At the higher concentrations of bilirubin and with reduction in pH of the buffer in the absence of antioxidants, the shift to lower wave lengths was reduced and 480–560 nm shoulder formation was increased. In the absence of antioxidants and EDTA at the lower concentrations of bilirubin and in more alkaline media, the reduction at 440 nm and the shift of maximal absorption to the shorter wave lengths was enhanced. At pH 12, stirring of antioxidant-EDTA-containing solutions of bilirubin resulted in neither a shift of maximal absorption to the shorter wave lengths nor the formation of 480–560 nm shoulder. The formation of 480–560 nm shoulder was accompanied by the visual appearance of turbidity. The formation of flocculants when a “solution” is agitated indicates that significant portions of the pigment were in fact, not in solution and must have existed previously as a finely dispersed colloidal sol or supersaturated solution which progressed to a colloidal sol.Spectral curves of bilirubin, therefore, may represent a composite resulting from four physical states of bilirubin: (1) bilirubin truly in solution with the spectral peak at 440 nm; (2) bilirubin in the fine colloidal dispersion with spectral characteristics similar to those of bilirubin in solution; (3) bilirubin flocculant giving 480–560 nm shoulder; and (4) oxidation products of bilirubin with the spectral peaks lower than 440 nm.Increasing the pH of the aqueous media containing bilirubin (0.05 mg/100 ml) from 7.4 to 12.0 increased the molar extinction coefficient of bilirubin, E4401M, 1cm, progressively to a maximum at pH 12 of 6.35 x 104. Very dilute bilirubin preparations (0.005–0.050 mg/100 ml) in aqueous media, pH 7.4, exhibited spectral evidence of rapid oxidation (more so at higher pH), but spectral shoulder formation was still observed after mechanical agitation. Thus, the solubility of bilirubin in 0.1 M phosphate buffer at pH 7.4 appears to be less than 0.005 mg/ 100 ml.SpeculationUnbound bilirubinin vivo, at concentrations exceeding albumin binding capacity and its aqueous solubility, is believed to exist either as a colloidal sol (micropolymer) or a flocculant (macropolymer). It is proposed that it is in the colloidal sol form (micropolymer) that bilirubin toxicity to brain, kidney, intestinal mucosa, erythrocyte, and other organs initially develops by a process of colloid to surface interaction.

ISSN:0031-3998    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

ExtractThe effect of 21 days of promethazine-HCI administration on hepatic bilirubin metabolism and transport was studied in adult rats. A significant increase in mean cumulative hepatic bilirubin uptake (84.5 ± 7.6 (SE)μg/100 g/min in controlsvs. 110.0 ± 4.3 in treated rats), mean hepatic glucuronide conjugation (1,330 ± 86 (SE)μg bilirubin conjugated/g liver/40 min in controlsvs. 1,713 ± 61 in treated rats), and mean maximal hepatic excretion (47.2 ± 4.9 (SE)μg/100 g/minvs. 63.5 ± 2.7) was observed in treated animals. Mean total liver weight and total hepatic protein also increased significantly.These observations suggest that promethazine is an inducer of protein and enzyme synthesis in rat liver and is capable of significantly stimulating the three major steps in hepatic disposal of bilirubin.SpeculationThe stimulatory effect of promethazine on bilirubin metabolism and transport introduces a second or alternate explanation for the reported effectiveness of the drug in ameliorating hyperbilirubinemia in human Rh erythroblastosis. Thus, the drug may either decrease bilirubin synthesis through inhibition of macrophage destruction of sensitized erythrocytes or by other immunosuppressive action, or it may enhance hepatic bilirubin disposal mechanisms. If the major effect of promethazine is stimulation of bilirubin metabolism and transport in the fetus, then one may question whether it has any advantage over other stimulatory agents, such as phenobarbital.

ISSN:0031-3998    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

ExtractAntibody-dependent cell-mediated cytotoxicity (ADCMC) was measured in a51Cr-release assay with antibody-sensitized human red blood cells (RBC) as target cells and nonimmune isologous or autologous mononuclear peripheral blood leukocytes (MPBL) as effector cells. ADCMC was readily demonstrable within 6 hr and was independent of exogenous complement (C'). The specificity of the ADCMC reaction was determined by the antiserum employed. Anti-A, anti-B, anti-D, and anti-c sera were all active in ADCMC; the specific lysis was between 35 and 50% with antiserum dilution of 1/1,000, using 105target cells and 106MPBL. Anti-C, anti-E, and anti-e sera had no detectable activity. Sephadex column separation suggested that this activity was by antibodies of the IgG class.Cord RBC from infants with RhD fetal-maternal incompatibility were lysed by autologous or isologous MPBL in the absence of exogenous antiserum. ADCMC was between 22% and 42% incases with high direct Coombs' test, but was negative with low direct Coombs' test as in five cases of ABO incompatibility.SpeculationIn hemolytic disease of the newborn, the precise mechanisms involved in the destruction of fetal erythrocytes sensitized with maternal antibodies are not well known. The experiments described in this report raise the possibility that ADCMC could be operativein vivo

ISSN:0031-3998    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

ExtractA system for the isolation and functional evaluation of fetal liver erythroblasts is described. Isolated erythroblasts were pre-pared from 14-day embryonic avian livers and incubated at various oxygen tensions (0, 5, 12, and 95%). The concentration of ATP in erythroblasts remained constant for at least 4 hr at 37°, but was rapidly reduced by incubation in nitrogen. Protein synthesis as measured by L-[14C]leucine incorporation into cell protein occurred at a linear rate in 5%, 12%, and 95% oxygen, whereas little protein synthesis occurred at 0% oxygen. The effect of hypoxia on the type of hemoglobin synthesized was studied in this system by isolating the hemoglobin A, hemoglobin D, and hemoglobin H fractions and determining the incorporation of L-[14C]leucine. The major fraction, hemoglobin A, contained most of the radioactivity; smaller amounts were present in hemoglobin D and hemoglobin H, respectively. The relative proportion of each hemoglobin synthesized was not altered by oxygen from 5% to 95%. These results argue against a direct effect of oxygen on the type of hemoglobin synthesized at this stage of development.SpeculationEarly in fetal development nonerythropoietin mechanisms for the regulation of erythropoiesis may exist. The hypoxic stimulus to erythropoiesis is mediated through erythropoietin in definitive erythroblasts, but may have a direct effect in primitive erythroblasts.

ISSN:0031-3998    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

ExtractFifteen red cell enzyme activities of growth-retarded patients with and without growth hormone (GH) deficiency were investigated before and after GH administration. The 15 enzymes were Hexokinase, phosphoglucomutase, glucose phosphate isomerase, phosphofructokinase, fructose diphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase, triosephosphate isomerase, 2,3-diphosphoglycerate mutase, 3-phosphoglycerate kinase, 3-phosphoglycerate mutase, enolase, pyruvate kinase, glycose-6-phosphate dehydrogenase, 6-phosphogluconic dehydrogenase, glutathione reductase.Sixty-six subjects were studied: 30 normal control subjects (group N) and 36 patients (aged 5–23 years) with short stature. Complete endocrine evaluation showed 21 (group I) to have GH deficiency (10 patients with isolated GH deficiency) and 15 (group II) to have normal hypothalamic and pituitary function except for two patients with a moderate hypothyroidism. Both had been receiving thyroid hormone treatment for a long time before our studies. All 36 patients were treated with 2 mg human growth hormone intramuscularly for 7 days.Before GH treatment no significant difference was observed between hematologic data ingroup I(GH deficiency) andgroup II(no GH deficiency). After GH therapy there was a significant increase in reticulocyte count in both groups of patients with short stature. The mean pretreatment value ingroup Iwas 1.294% ± 0.084 (SEM); the mean post-treatment value was 2.081% ± 0.287 (SEM),P< 0.005. The mean pretreatment value ingroup IIwas 1.0% 0.184 (SEM); the mean post-treatment value was 1.407% ± 0.193(SEM),P< 0.01.Ingroup II(no GH devidiency) mean pretreatment erythrocyte enzyme activities were not significantly different from those activities observed in normal control subjects (group N). However, in patients who lacked GH, the pretreatment activities of five red cell enzymes (glucose phosphate isomerase, triosephosphate isomerase, glyceraldehyde-3-phosphate dehydrogenase, 2,3-diphosphoglycerate mutase, 3-phosphoglycerate kinase) were significantly decreased before GH administration compared with the values in normal control subjects. The reduction in a further red cell enzyme (3-phosphoglycerate mutase) was statistically not significant.With GH treatment eight red cell enzyme activities showed a significant increase, one of them (hexokinase) significantly rising in both groups of patients. The remaining seven erythrocyte enzymes (3-phosphoglycerate mutase, glucose phosphate isomerase, triosephosphate isomerase, 2,3-diphosphoglycerate mutase, enolase, pyruvate kinase, glucose-6-phosphate dehydrogenase) exhibited significantly elevated activities only in patients lacking GH. In three of these enzymes the increase was significantly above the control value.Enzyme activities which were significantly decreased before GH administration rose significantly after GH therapy except for two enzyme activities (3-phosphoglycerate kinase and glyceraldehyde-3-phosphate dehydrogenase). The data may suggest the presence of a younger red cell population after GH administration.SpeculationThe increase in red cell enzyme activities after GH treatment is supposedly due to stimulation of erythropoiesis by growth hormone. An additional stimulatory effect of GH on nucleated red cell enzyme synthesis is less likely but cannot be definitively excluded.

ISSN:0031-3998    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

ExtractRats were subjected to nutritional growth retardation either from conception to 5 postnatal days of age (fetal and neonatal restriction (FNR) group), or from 5 to 25 postnatal days of age (infantile restriction (IR) group). The FNR group may serve as a model for the human small-for-dates baby.At 20 weeks of age cerebellum, midbrain, and cerebrum were significantly reduced in weight by 4%, 5%, and 4%, respectively, in FNR animals when compared with controls. Only cerebellum and midbrain were affected in IR rats of the same age, but in both regions the percentage deficits (8% and 9%, respectively) were greater than in FNR animals. Both cerebellum and midbrain weighed significantly less in IR than in FNR rats.The timing of nutritional growth retardation appeared to be of little consequence to the regional brain turnover of 5-hydroxytryptamine in adulthood. The rate of synthesis in the hippocampus of both FNR and IR animals was significantly faster (67% and 75%, respectively) than in controls. The increased turnover could perhaps represent “overactivity” of those 5-hydroxytryptaminergic neurons terminating in the hippocampus.Some differences in the behavior of the previously undernourished adult animals were also evident. On the fifth day of testing, control rats were most venturesome in the open field. Eighteen control rats left the edge zone within 2 min, whereas only 8 FNR and 11 IR rats did so. Most animals froze immediately after a 7-sec exposure to a loud electric bell. The delay before moving about again differentiated the three groups. FNR rats took longest to move out of the area in which they froze.SpeculationLasting changes have been shown here in rats undernourished at a stage of development commonly implicated in the growth retardation of many human small-for-dates infants. It would therefore be unwise at this stage to conclude that such babies emerge unscathed from intrauterine growth retardation.

ISSN:0031-3998    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

ExtractThe present study using immunologic methodology confirms previous observations from this laboratory of an absence of a protease component with arginine esterase activity in plasma of patients with cystic fibrosis. In this study, the pooled plasma from control individuals was activated and partially purified after adsorption on columns of soybean trypsin inhibitor conjugated to Sepharose 4B followed by elution with benzamidine. The fraction was further purified by isoelectrofocusing on polyacrylamide gels. Proteins around the pI range of 5.5 were eluted and utilized to prepare an antiserum. Immunoelectrophoresis of activated plasma samples from control subjects and patients with cystic fibrosis was performed utilizing the antiserum. In controls, four precipitin arcs with residual esterase activity were observed, whereas only three were seen in plasma from patients with cystic fibrosis. Double gel diffusion experiments using specific antisera ruled out the presence of trypsin, chymotrypsin, plasminogen, prothrombin, C1 esterase,α1-trypsin inhibitor, and inter-α-trypsin inhibitor in the concentrated benzamidine eluate. The antisera toα2-macroglobulin gave an immunoprecipitate which was readily stained for proteolytic activity. On immunoelectrophoresis, theα2-macroglobulin precipitin band corresponded to the band absent in plasma of patients with cystic fibrosis. In contrast, theα2-macroglobulin levels were similar in plasma of control subjects and patients with cystic fibrosis. Using the antiserum to the protein fraction with a pI of 5.5 in cross immunoelectrophoresis, three “rockets” with proteolytic activity could be demonstrated in control plasma. One specific enzyme-active “rocket” was absent in plasma of patients with cystic fibrosis. In a double blind study of 15 control samples and 15 samples from patients with cystic fibrosis, a specific “rocket” was shown to be present in 13 control samples and absent in 14 cystic fibrosis samples.α2-Macroglobulin was determined by both an immunologic procedure and by its trypsin binding (trypsin protein esterase concentration). The ratio of the immunologic assay to the biologic activity assay was 90 for the normal plasma samples and only 65 for cystic fibrosis samples.SpeculationThe absentα2-macroglobulin-protease complex in plasma of patients with cystic fibrosis might reflect a molecular defect in either a protease with arginine esterase activity or within theα2-macroglobulin molecule.

ISSN:0031-3998    

出版商:OVID    

年代:1976

数据来源: OVID